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Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses.

Huang B, Liang F, Zhong L, Lin M, Yang J, Yan L, Xiao J, Xiao Z - Sci Rep (2015)

Bottom Line: Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics.However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses.Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, PR China [2] Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, PR China.

ABSTRACT
Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curve) and could be fitted to an exponential decay equation, which showed two components, the theoretical minimum latency and stimulus-dependent delay. From the latency-intensity curves, the changes of these two components (∆L and ∆I) were extracted during anesthesia. ∆L and ∆I monitored the effect of pentobarbital on nerve fibers and synapses. Pentobarbital can induce anesthesia, and two side effects, hypoxemia and hypothermia. The hypoxemia was not related with ∆L and ∆I. However, ∆L was changed by the hypothermia, whereas ∆I was changed by the hypothermia and anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses. When eliminating the temperature factor, ∆I monitors the anesthesia effect on synapses.

No MeSH data available.


Related in: MedlinePlus

Changes in SPO2, temperature, ∆L and ∆I in warming mice.(a) SPO2- and temperature-time curves (M20150325). (b) Latency-intensity curves from M20150325 for all recording sessions lasting 110 min. (c) Data fitting to DCASF. Data were presented as those in Fig. 4c. (d) ∆L- and ∆I-time curves obtained from Fig. 7b. (e) ∆L- and temperature-time curves of five mice. (f) Normalized ∆I-time curves of five mice and the fitting curves to GaussAmp equation (cyan curve,, R2 = 0.773, y0 = 1.208, A = −92.980, xc = 7.112, w = 2.073), and SPO2-time curves of five mice.
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f7: Changes in SPO2, temperature, ∆L and ∆I in warming mice.(a) SPO2- and temperature-time curves (M20150325). (b) Latency-intensity curves from M20150325 for all recording sessions lasting 110 min. (c) Data fitting to DCASF. Data were presented as those in Fig. 4c. (d) ∆L- and ∆I-time curves obtained from Fig. 7b. (e) ∆L- and temperature-time curves of five mice. (f) Normalized ∆I-time curves of five mice and the fitting curves to GaussAmp equation (cyan curve,, R2 = 0.773, y0 = 1.208, A = −92.980, xc = 7.112, w = 2.073), and SPO2-time curves of five mice.

Mentions: The SPO2 of mouse (M20150325) decreased at initial 20 min, then increased and kept relatively steady during the anesthesia (Fig. 7a, the blue curve with stars to the left ordinate). The SPO2 were not lower than 91%. With body warming, although the temperatures measured from this mouse slightly decreased at initial 20 min after pentobarbital injection, the temperatures were normal and relative steady during recording. The fluctuation range of temperatures did not exceed 1 ºC (Fig. 7a, the red curve with triangles to the right ordinate). The AEP latency from this mouse also exponentially decayed with acoustic intensity (latency-intensity curves) (Fig. 7b), but the range of latency changes was much less than those without body warming (Figs 4b, 5a). By performing DCASF as that to the data in Figs 4c, 5b, all latency-intensity curves in Fig. 7b could be fitted to Equation (2) with L0, I0, K and τ were respectively 14.683, 47.732, 7.013 and 18.859 from the fit to Equation (1) (Fig. 7c, the red curve, R2 = 1.000), and their ∆L and ∆I during anesthesia were obtained (Fig. 7d). Not surprising, the ∆L kept relatively steady during anesthesia and the fluctuation range of ∆L did not exceed 0.6 ms (Fig. 7d, the red curve with triangles to the left ordinate). However, the ∆I gradually decreased as anesthesia time with some fluctuations (Fig. 7d, the blue curve with stars to the right ordinate).


Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses.

Huang B, Liang F, Zhong L, Lin M, Yang J, Yan L, Xiao J, Xiao Z - Sci Rep (2015)

Changes in SPO2, temperature, ∆L and ∆I in warming mice.(a) SPO2- and temperature-time curves (M20150325). (b) Latency-intensity curves from M20150325 for all recording sessions lasting 110 min. (c) Data fitting to DCASF. Data were presented as those in Fig. 4c. (d) ∆L- and ∆I-time curves obtained from Fig. 7b. (e) ∆L- and temperature-time curves of five mice. (f) Normalized ∆I-time curves of five mice and the fitting curves to GaussAmp equation (cyan curve,, R2 = 0.773, y0 = 1.208, A = −92.980, xc = 7.112, w = 2.073), and SPO2-time curves of five mice.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526847&req=5

f7: Changes in SPO2, temperature, ∆L and ∆I in warming mice.(a) SPO2- and temperature-time curves (M20150325). (b) Latency-intensity curves from M20150325 for all recording sessions lasting 110 min. (c) Data fitting to DCASF. Data were presented as those in Fig. 4c. (d) ∆L- and ∆I-time curves obtained from Fig. 7b. (e) ∆L- and temperature-time curves of five mice. (f) Normalized ∆I-time curves of five mice and the fitting curves to GaussAmp equation (cyan curve,, R2 = 0.773, y0 = 1.208, A = −92.980, xc = 7.112, w = 2.073), and SPO2-time curves of five mice.
Mentions: The SPO2 of mouse (M20150325) decreased at initial 20 min, then increased and kept relatively steady during the anesthesia (Fig. 7a, the blue curve with stars to the left ordinate). The SPO2 were not lower than 91%. With body warming, although the temperatures measured from this mouse slightly decreased at initial 20 min after pentobarbital injection, the temperatures were normal and relative steady during recording. The fluctuation range of temperatures did not exceed 1 ºC (Fig. 7a, the red curve with triangles to the right ordinate). The AEP latency from this mouse also exponentially decayed with acoustic intensity (latency-intensity curves) (Fig. 7b), but the range of latency changes was much less than those without body warming (Figs 4b, 5a). By performing DCASF as that to the data in Figs 4c, 5b, all latency-intensity curves in Fig. 7b could be fitted to Equation (2) with L0, I0, K and τ were respectively 14.683, 47.732, 7.013 and 18.859 from the fit to Equation (1) (Fig. 7c, the red curve, R2 = 1.000), and their ∆L and ∆I during anesthesia were obtained (Fig. 7d). Not surprising, the ∆L kept relatively steady during anesthesia and the fluctuation range of ∆L did not exceed 0.6 ms (Fig. 7d, the red curve with triangles to the left ordinate). However, the ∆I gradually decreased as anesthesia time with some fluctuations (Fig. 7d, the blue curve with stars to the right ordinate).

Bottom Line: Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics.However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses.Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, PR China [2] Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, PR China.

ABSTRACT
Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curve) and could be fitted to an exponential decay equation, which showed two components, the theoretical minimum latency and stimulus-dependent delay. From the latency-intensity curves, the changes of these two components (∆L and ∆I) were extracted during anesthesia. ∆L and ∆I monitored the effect of pentobarbital on nerve fibers and synapses. Pentobarbital can induce anesthesia, and two side effects, hypoxemia and hypothermia. The hypoxemia was not related with ∆L and ∆I. However, ∆L was changed by the hypothermia, whereas ∆I was changed by the hypothermia and anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses. When eliminating the temperature factor, ∆I monitors the anesthesia effect on synapses.

No MeSH data available.


Related in: MedlinePlus